>No comment on effectiveness, but for anyone who is going to do this, make sure to dilute the vinegar with some water.

Oh jeez, woopsie. Yeah, forgetting to do that would certainly cause a bit of sore throat. Or 3rd degree burns.

1 tsp apple cider vinegar mixed in a full glass of water.

It also helps to drink with a straw to avoid residual acid on the teeth (although the water already diluted it enough).